1. Field of the Invention
The present invention relates to an alarm and antitheft system for an automotive vehicle, and more particularly to such a system connected with conventional automotive electrical circuits to provide an alarm and to disable the ignition and starting systems of the vehicle when unauthorized use of the vehicle is attempted, to provide a signal when lights of the vehicle are left on with the ignition system de-energized, and to select these functions or conventional operation of the vehicle by either key locked or momentary actuation of a suitable element.
2. Description of the Prior Art
Vehicles have been provided with antitheft systems and with alarm systems having elaborate functions, mechanisms, and circuitry. However, as is well known, the majority of thefts of automotive vehicles occur when the ignition key is inadvertently left in an unoccupied vehicle. A system to frustrate unauthorized use of a vehicle under these circumstances would, therefore, prevent the majority of automotive vehicle thefts without unnecessary expense or inconvenience due to features which are rarely of benefit and are, therefore, likely to be inadvertently or intentionally disabled by the owner of a vehicle.
Automotive alarm systems and antitheft systems which include switching devices connected to conventional ignition and horn circuits of a vehicle are well known. A system including such a device, hereinafter referred to as the "earlier system," is disclosed in U.S. Pat. No. 3,569,931 issued to the applicant on Mar. 9, 1971. A copy of this patent is enclosed in connection with the "Prior Art Statement."
The subject invention includes several improvements in the earlier system to provide greater flexibility in operation, to provide a system which is simpler and more economical to install on an existing vehicle and to include in a vehicle when initially manufactured, and to accommodate and advantageously to utilize features of automotive vehicles that have become prevalent since application was made for patent of the earlier system.
The earlier system included a manually actuatable element to transfer the system between an alarm condition and a running condition. This element was either a push-button or was key lockable. However, the use of a system having such an element is facilitated by such an element having both push-button and key-lockable modes of operation.
The earlier system provided a switching device which electrically interrupted the connection between a distributor and a coil of an existing vehicle ignition system to that "hot wiring" to the coil did not permit unauthorized operation of the vehicle. When the previous system was conceived, automotive vehicles were infrequently equipped with hood latches and with stransmissions which did not allow starting the engine of a vehicle by moving the vehicle. However, presently manufactured automotive vehicles are provided with lockable hoods which impede hot wiring and, typically, are provided with an automatic transmission which does not allow starting the engine other than by the usual electric starting system. It is, therefore, advantageous to provide an antitheft system which disables the starting system of an automotive vehicle to prevent its unauthorized use.
An improved system having these advantages is especially advantageous if its arrangement is simple and if the length of wiring required is relatively short. It is particularly desirable to limit the number of penetrations of electrical conductors through the firewall of a vehicle and to take advantage of the proximity in a vehicle of elements of an alarm and antitheft system to conventional lighting and alarm elements to provide a signal that the vehicle lights are inadvertently illuminated and, in general, to provide simplified and economical wiring arrangements.